Conveying caster means

ABSTRACT

A swiveling base carrying a low profile axle supporting structure with three or more caster wheels arranged in a triangular supporting and conveying pattern for distributing the load and thereby being capable of continuously achieving automatic alignment with associated receiving cargo. In addition, the feature of receiving cargo is improved by the conical edge design of the swivel base and the spring loaded mounting of the base structure.

111 3,724,022 Apr. 3, 1973 United States Patent [1 1 Alberti et al.

[54] CONVEYING CASTER MEANS 7s lnventorsz'john mam; Seattle"; "Williamw. ""7" McCall Nanninga, Bellevue, both of wash Assistant Exammer-DorisL. Troutman Attorney-Glenn Orlob, Kenneth W. Thomas and Nicolaas DeVogel[73] Assigneef The Boeing Company, Seattle,

Wash.

[57 ABSTRACT A swiveling base carrying a low profile axle suppo [22]Filed: Feb. 1, 1971 [2l] Appl. No.: 111,396

rting structure with three or more caster wheels arranged in [52] US. atriangular supporting and conveying patter f di [51] Int. 91/00 t ib tithe load and thereby being capable of con- Field of Search 248/24tinuously achieving automatic alignment with associated receiving cargo.In addition, the feature of receiving cargo is improved by the conicaledge design of the swivel base and the spring loaded mounting of thebase structure.

S T. N m MA :IP CS SE m e mm e m H N ..U P "D 16/47 7 Claims, 7 DrawingFigures Clifton M a n o d c m 2 6 9 l l 8 CONVEYING CASTER MEANSBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to cargo conveyor systems and more particularly to a swivelablecargo supporting caster apparatus for receiving, supporting andtransferring cargo on cargo decks in aircraft.

2. Prior Art Reviewing the existing art, there appear to be variouspatents concerning cargo carrying casters, and a thorough search showedthat the most pertinent art relative to the present invention was foundin the U.S. Pat. No. 3,047,904 issued to J. G. MacDonald.

In general, the basic design to most casters of the type discussedherein involves a mounting means, a swiveling base on the mounting meansand a wheel or wheels rotating on a shaft which are supported on theswiveling base. The above-mentioned US. patent reference has the basiccaster structures and an added feature of two mis-aligned axles whichserves a particular purpose and warranted patentability.

The present invention improves over the prior art by its load carryingperformance which is due to a unique triangular support means. Inaddition, the herein-disclosed caster takes a minimum of space as far asdimensions for installation are concerned yet has the capacity to carry7,500 to 8,000 pounds rather than the 1,750 to 2,000 pounds carryingability of the most efficient existing casters available.

The ability to carry such a high load is accomplished by a unique andnovel solution explained hereinafter.

SUMMARY OF THE INVENTION The present invention applies basically tocargo carrying aircraft and in this instance was designed specificallyas part of the main deck cargo system for the Boeing 7473.

The conveyor caster means or caster comprises a floor-mounted basestructure carrying a ring-shaped bearing. A circular axle supportstructure is rotationally carried by the bearing. The axle support hasthree axles, each provided with a cargo support wheel and the threewheels are so positioned that a triangular or three-point support isprovided to associated cargo placed thereon.

This triangular support pattern formed by the three tangent points ofthe wheels divides the cargo in an even load carrying distribution but,also, because the pattern is located next to the diameter or almost inhalf the segment of the circular axle support carried by the ringbearing, the arrangement will act as a pivot for self-aligning whencargo is shoved onto it.

Thus this triangular pattern serves two main functions, loaddistribution and self-aligning of the caster with the cargo. Inaddition, there are other features which are important, such as springsprovided at each corner of the mounting base so that extra resiliency isachieved when cargo is initially received from a loading platform. Forinstance, the 7473 airplane has approximately 800 casters of the presenttype evenly distributed over the main deck cargo floor and the first to8 feet of the cargo entrance uses casters with the spring-loadedmounting for absorbing initial weight impact of the cargo when movedinside the airplane onto the floor.

In summary, the features which are unique to the subject invention arethe low profile of the caster unit; the three-wheel triangular designarrangement accomplished within minimum space parameters for maximumeffective load-carrying capability; the caster wheel protection providedby the conical design of the axle support structure which prevents cargofrom hitting and damaging wheels broadside and the selfpivoting andaligning with the cargo of the axle support structure upon first contactwith the approaching car- It is therefore an object of the presentinvention to provide for a caster unit which has high load-carrying,self-aligning, low profile, and wheel protective features designed withminimum space parameters for maximum required performance.

It is another object of the present invention to provide for a cargoreceiving, supporting and conveying caster having triangularlypatterned, rotationally supporting means on a substantially horizontalplane.

Other objects and advantages will become apparent from the followingdescription taken in conjunction with the accompanying drawingshereinafter explained in further detail.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of thecaster;

FIG. 2 is a plan view of the caster;

FIG. 3 is a tray arrangement with three installed casters as used inairplane cargo areas;

FIG. 4 shows the basic axle location with design parametersdiagrammatically illustrated;

FIG. 5 is a section view taken from FIG. 2 along line 55;

FIG. 6 is a section view taken from FIG. 7 along line 6-6;

FIG. 7 shows a second embodiment of the basic caster in plan viewfashion.

DESCRIPTION OF THE INVENTION The drawings illustrate by way of example,not by way of limitation, two forms of the preferred embodiments of theinvention wherein like reference numerals designate corresponding partsin the several views. With reference to FIGS. 1 and 2, there isillustrated a caster 10 which includes mainly a floor mounting base 12,a thereon spring mounted swiveling base structure 14, a thereonrotationally mounted circular axle support structure 16 with casterwheels 18, 20 and 22.

The caster 10 is normally mounted between channels 26 and 28 within acargo floor and since the present invention was developed specificallyfor use in aircraft cargo areas such casters are generally pre-mountedin trays 30 as shown in FIG. 3.

The various intermediate components of the caster 10 are shown in thesectional view of FIG. 5 taken along each caster wheel axle.

Heavy duty springs 40 provide for a resilient fastened connectionbetween the floor base 12 and the swivel base structure 14; however,these springs are used basically to obtain optimum load distributionover a group of casters in highly loaded areas and also in cases wherecargo is received by the caster 10 from an elevated surface and more orless provide the caster 10 with a shock absorbing action. Thus, whencargo is slid upon the caster 10, only then such springs 40 can beomitted and the swivel base structure could even be mounted directly tothe floor without the floor mounting base 12, which would provide anadditional reduction to the already shallow height of the caster 10. Ascan be noted, the caster is barely raised above the floor level 42 andthe parts above the floor level 42 are rotationally engaged for theleast frictional providing purposes. Therefore, a ring bearing 44supports the axle support 16 on the swivel base structure 14. The axlesupport carries axles 48-50 and 52, and each axle carries a bearing58-60 and 62, respectively, for rotationally supporting the casterwheels 18-20 and 22, respectively.

The above main components carry the intermediate components as describedbut this arrangement has been designed within the dimensions of thebases 14 and 16 and so that a maximum performance within minimumavailable space parameters is geometrically obtained.

The circle 70 in FIG. 4 represents the periphery of the axle supportstructure 16 and the line 71 represents the diameter passing over thecenter 72 of the circle 70. Rotation of the circle 70 by a forceparallel thereto can only be accomplished by friction at any place nextto the center 72. Accordingly, a movable arrangement is made in asegment 73 located next to the diameter 71, which segment 73 is borderedby a first secant 74 and part of the periphery 70 indicated by 75. Tosupport a load within a' predetermined area shaped as the segment 73,triangularly spaced support points 76, 77 and 78 will be most efficientand carry this load in equal distribution. Because the load is not onlysupported but also has to be conveyed or transferred parallel to thecircle 70, caster wheels or rollers on axles are to be installed at eachpoint 76, 77 and 78; however, each caster wheel should have the largestperiphery or diameter possible and, therefore, a second secant 79parallel to the first secant 74 limits the triangular spaced pattern topoints 76, 77, 78 due to the maximum radius of each caster wheel.

The caster wheel radius mounted on point 78 will interfere or cutperpendicularly the first secant 74 so that two axles 48 and 50 appearnecessary rather than a one-axle support for two caster wheels; however,various modifications could be made as shown in FIG. 7 where a doublecenter caster wheel arrangement 80 and 82 is used in caster 84 but itsoperation and design are within the basic engineering concept of thethree wheel caster described above.

For this and other reasons it can be stated that, while the preferredembodiments of the invention have been herein described and illustrated,it should be understood that various modifications and alterations maybe made without departing from the spirit of the invention or scope asdefined by the appended claims.

Now, therefore, we claim:

1. A caster for receiving and conveying cargo comprising:

a. a base structure carrying a ring bearing;

b. a circular axle support structure disposed in said bearing forrotation about a substantially vertical axis;

c. a first axle, a second center axle, and a third axle substantiallyhorizontally carried by said circular axle support, wherein said firstand said third axle are positioned apart and in alignment with oneanother coincident with a first secant of said circular support, andsaid second center axle is positioned coincident with a second smallersecant parallel to said first secant within said first secant segmentand adjacently located to said apart position of said first and thirdaxles, and

. a wheel mounted for rotation about each of said axles and arrangedsymmetrically with respect to a radius line normal to said first andsecond secants so as to be positioned in a triangular cargo supportpattern for movement of the cargo in a direction substantially parallelto said radius line.

2. A caster for receiving and conveying cargo comprising:

a. a base structure carrying a ring bearing;

b. a circular axle support structure disposed in said bearing forrotation about a substantially vertical axis;

. a first axle, a second center axle, and a third axle substantiallyhorizontally carried by said circular axle support, wherein said firstand said third axle are positioned apart and in alignment with oneanother coincident with a first secant of said circular support, andsaid second center axle is positioned coincident with a second smallersecant parallel to said first secant within said first secant segmentand adjacently located to said apart position of said first and thirdaxles;

d. caster wheels rotationally carried by each of said axles so that saidwheels are arranged in a triangular supporting and conveying pattern forcarrying associated cargo on a substantially horizontal plane formed byeach said caster wheel cargo contacting tangent point; and

. said base structure is mounted to an associated cargo floor by meansof spring resilient fasteners so that initial load impact when receivedis distributed and absorbed.

3. A caster for receiving and conveying cargo as claimed in claim 2wherein said first, said center axle and said third axle are sopositioned in said segment that said caster wheels have largest possibleand equal diameters allowable within space parameters present in saidsegment of said circular axle support.

4. A caster for receiving and conveying cargo as claimed in claim 3wherein said axle support is provided with an horizontally disposedupper surface having a slightly inclined angle for guiding saidassociated received cargo onto said wheels tangent points.

5. A caster for receiving and conveying cargo as claimed in claim 4wherein said wheels are provided with a convexly shaped riding surface.

6. A caster for receiving and conveying of cargo 'as claimed in claim 5wherein at least three caster wheels are used within said segment.

7. A caster for receiving and conveying of cargo as claimed in claim 6wherein said convexly shaped riding surface of said wheels and saidinclined angle of said axle support are in alignment with one anotherfor smooth reception of said associated cargo on said wheels.

1. A caster for receiving and conveying cargo comprising: a. a basestructure carrying a ring bearing; b. a circular axle support structuredisposed in said bearing for rotation about a substantially verticalaxis; c. a first axle, a second center axle, and a third axlesubstantially horizontally carried by said circular axle support,wherein said first and said third axle are positioned apart and inalignment with one another coincident with a first secant of saidcircular support, and said second center axle is positioned coincidentwith a second smaller secant parallel to said first secant within saidfirst secant segment and adjacently located to said apart position ofsaid first and third axles, and d. a wheel mounted for rotation abouteach of said axles and arranged symmetrically with respect to a radiusline normal to said first and second secants so as to be positioned in atriangular cargo support pattern for movement of the cargo in adirection substantially parallel to said radius line.
 2. A caster forreceiving and conveying cargo comprising: a. a base structure carrying aring bearing; b. a circular axle support structure disposed in saidbearing for rotation about a substantially vertical axis; c. a firstaxle, a second center axle, and a third axle substantially horizontallycarried by said circular axle support, wherein said first and said thirdaxle are positioned apart and in alignment with one another coincidentwith a first secant of said circular support, and said second centeraxle is positioned coincident with a second smaller secant parallel tosaid first secant within said first secant segment and adjacentlylocated to said apart position of said first and third axles; d. casterwheels rotationally carried by each of said axles so that said wheelsare arranged in a triangular supporting and conveying patterN forcarrying associated cargo on a substantially horizontal plane formed byeach said caster wheel cargo contacting tangent point; and e. said basestructure is mounted to an associated cargo floor by means of springresilient fasteners so that initial load impact when received isdistributed and absorbed.
 3. A caster for receiving and conveying cargoas claimed in claim 2 wherein said first, said center axle and saidthird axle are so positioned in said segment that said caster wheelshave largest possible and equal diameters allowable within spaceparameters present in said segment of said circular axle support.
 4. Acaster for receiving and conveying cargo as claimed in claim 3 whereinsaid axle support is provided with an horizontally disposed uppersurface having a slightly inclined angle for guiding said associatedreceived cargo onto said wheels'' tangent points.
 5. A caster forreceiving and conveying cargo as claimed in claim 4 wherein said wheelsare provided with a convexly shaped riding surface.
 6. A caster forreceiving and conveying of cargo as claimed in claim 5 wherein at leastthree caster wheels are used within said segment.
 7. A caster forreceiving and conveying of cargo as claimed in claim 6 wherein saidconvexly shaped riding surface of said wheels and said inclined angle ofsaid axle support are in alignment with one another for smooth receptionof said associated cargo on said wheels.